INTRODUCTION. 53 



inflamed surfaces, is soluble in the blood, from which when 

 drawn it readily coagulates. 



It can be obtained from the blood, by stirring it briskly 

 with a rough stick, when it will appear in the form of fibres 

 or threads. Vegetable acids, their salts, and caustic alkalies 

 prevent coagulation. 



Its chemical elements are 



Nitrogen, 19.934, 



Carbon, 53.360, 

 Hydrogen, V.021, 



Oxygen, 19.685, in the hundred parts. 



Casein exists most abundantly in milk, but is also found 

 in the blood, saliva, bile, pancreatic fluid, lens, and else- 

 where. In solution it is of a pale yellow, coagulates by 

 heat, acids, alcohol, and rennet. 



It is soluble in water, and in this state has the consist- 

 ence of mucilage. 



When dried it is of an amber color, and very friable. 



Cheese is composed of dried casein and butter. Accord- 

 ing to Mulder its chemical elements are in one hundred 

 parts 



Nitrogen, 15.95, Hydrogen, 6.9T, 



Carbon, 55.10, Oxygen, 21.62. 



These four organic elements constitute the great proxi- 

 mate principles of animal formation. 



And the albumen, fibrin, and casein, seem to be formed 

 from the protein, or more properly speaking, only differ 

 from it by having in addition a little sulphur and phos- 

 phorus in combination. 



Protein, it has been stated, is always found in the albu- 

 minous vegetables, and has the same constitution in them 

 as in the animal frame. Hence, we can readily under- 

 stand how and why it is, that vegetable matter is so read- 

 ily converted into animal, and so important in sustaining 

 life. 



